Four vs Five point

[firebob]

I was going racing awhile back and when I went to get the car teched the guy was giving me some grief about the harness I had installed. Everything was anchored in the proper places but he said because I didn't have the submarine belt it could possibly slip up and cause damage to the upper torso in a bad crash. Yeah maybe. Now I was thinking that almost anything would be better than the 40 year old stitched up seatbelts and the separate shoulder belt that has been sitting in the sun forever but I guess that's just me. So I pulled out the RCI harnesses and put back my old seatbelts. You should have seen the look on my ride along instructor's face when I explained to him how the seatbelt arrangement works in my 69 Firebird. I thought he was going to get out right then.

Robert

[406 Q-ship]

I would agree that 5 point is better but 4 point is still way better than any 40 year old OEM belts. I think that tech inspector needs to reevaluate his priorities.

[MonzaRacer]

Any idiot that bad mouths a 4 point better reread a lot of rules, I wrecked back in 86 in an 86 Areocoupe Monte Carlo and it was 4 endos the rolled over 3 more times and all I had was a 4 way and never moved.
In a proper seat a 4 way wont let you out even without a antisubmarine belt.
And also as for me I am going to have my harness in my car, if ii will probably never use the antisubmarine belt.

[NOT A TA]

I had an instructor refuse to get in my Firebird when I had stock belts and seats. Since instructors have been around the tracks a while they've seen all kinds of wrecks occur. They're getting in an unknown car, where they don't have control, and a driver they know doesn't have much experience.

I can't blame them for not wanting to take the chance of increased injury due to 30 or 40 year old deteriorated seatbelts in cars that weren't designed with modern crash technology. Same thing goes for incorrectly installed equipment or mismatched pieces of equipment. It's a lot of extra risk just to get a discount on their entry fees.

[John Wright]

4/point is still say better than any 40 year old OEM belts. I think that tech inspector needs to reevaluate his priorities.
I agree....

so they were saying that using the factory belts is OK, but a 4 pt isn't?

[FULMNTE]

Check our the 4 pt seat belt by Schroth, they have a specific Anti-Submarine Feature...

[NOT A TA]

I ran the Schroth 4 points with ASM in my Firebird for a while. Some tech guys (particularly at drag strips) gave me a hard time about them even after explaining what they did. I liked those harnesses very much. They were much more comfortable than using the 5 points I had in other cars on the street and work with hinged seats.

When I had a cage installed I moved up to 6 point Schroths and solid back seats. The 6 point seems more comfortable than the 5s I've had.

[Twentyover]

[QUOTE=MonzaRacer;653649]Any idiot that bad mouths a 4 point better reread a lot of rules, I wrecked back in 86 in an 86 Areocoupe Monte Carlo and it was 4 endos the rolled over 3 more times and all I had was a 4 way and never moved.
In a proper seat a 4 way wont let you out even without a antisubmarine belt.
.....QUOTE]

Count me an idiot. Anecdotal experience, while interesting reading, is pretty much irrelevant. The fact that you survived w/ a 4 point does not mean additional straps are ineffective. In the 50's a lot of drivers wanted to be thrown from the car to increase survivability. Rational analysis of numerous impacts shows that the cars structure absorbs impact better than your noggin. Perhaps the fact that some of them survived pretty horrific incidents by being thrown from the car should be the basis for elimination of any rules requirement for restraints at all. Using your logic, since at least one survived, the elimination of requirement is a rational rules change.

Addition of sub straps to rules is based on the review of a number of accidents. If you could guarantee that every wreck will have exactly the same impact direction and magnitude as yours, your argument would be valid. Since you can't, your anecdotal tale is an interesting footnote in history, nothing more.

It is my OPINION a modern factory 3 point is superior to a 4 point (Schroth's design excepted), as the unrestrained shoulder moves forward, forcing the lap belt to perform the anti sub function, and not holding the shoulder in place limiting head relocation for when you have a melon crusing roof collapse (in non-hooped cars)

In a hard frontal impact, both the lap and shoulder belts will stretch. As you chest pulls against the shoulder belts, they will tend to lift the lap belt away from you hips and relocate it more towards your jelly filled center, so internal organs are damaged, rather than the skeleton carrying the load.

[MonzaRacer]

The point of the 5th strap is to keep you from sliding out from under the harness, as I stated in a proper race seat with properly installed and adjusted 4 point you will never move barring a failure of something. We had older fiberglass racing buckets with padded covers, still legal in 86 but were out after 86. the bucket seats sides kept me in and the harness kept me in the seat, I do believe after a certain speed there should be what used to be called a "whip strap" fastened to the helmet but now Hans devises have made them obsolete.
Had one on my helmet and when the car went up on the nose it slide , while straight up and down for about 20 feet(by skid marks) then endoed 4 times, then tipped/laid over and roled 3 more, with out that strap I would have had a VERY sore neck. way it was I barely had bruise on one shoulder.
Big trick with any good 4 OR 5 point harness is that it be taught but not super tight, the reason is if its loose you accelerate into it and the harness wont hold you properly. And can fail.

[Jim Nilsen]

I have 5 point harnesses in my car and when I 1st was setting them up I didn't have the submarine belt installed yet. the one thing I noticed right away when I installed the 5th belt was how much it helped with the adjustment of the shoulder harnesses. With the sub belt you don't get the lapbelt rising up on your torso. I can strap myself in much better with the sub belt there and have the lapbelt where it belongs and it feels much more comfortable. Feeling comfortable is a big thing when you are cornering and braking hard and if it starts to bind you or hurt you the distraction is not good.

When going to the track I also found it was best to find an instructor who is about he same size as you are if you are brave enough to let them drive your car, it makes it so you don't have to totally rearrange your belts to fit each time because the normal adjustments are close enough.

After using both 4 and 5 point belts I would truly recommend the 5 point harness and the cost is not much more if any.

[parsonsj]

On Project Unfair, I've been working with Joe Marko at HMS Motorsports about the roll cage, seats, and harnesses. He consults weekly with NASCAR (attending each race to support the various race teams).

On the subject of 4 pt harnesses, he says that they are usually inferior to the OEM 3 pt seat belt for the submarine problems noted above. His preference is a 6 point, rather than the 5 pt. The 6 pt works better by adding additional restraint around the upper leg (the strongest part of the human anatomy), rather than just holding the lap belt down as a 5 pt does. And... the 6 pt is easer to fabricate since you don't need a hole in the middle of the seat.

jp

[The WidowMaker]

The point of the 5th strap is to keep you from sliding out from under the harness

thats not completely true. yes they keep you from sliding out, but as others have stated, their most important job is to keep the lap belt from rising to your abdomen.

[pedro]

His preference is a 6 point, rather than the 5 pt. The 6 pt works better by adding additional restraint around the upper leg (the strongest part of the human anatomy), rather than just holding the lap belt down as a 5 pt does. And... the 6 pt is easer to fabricate since you don't need a hole in the middle of the seat.

jp

Is it all 6pts that don't need a hole in the middle of the seat? Looking at the instructions on schroths web site they have one model (f-model) that mounts to the lap belt location, the other two seem to go through the seat. How easy are they to get in and out of?

I did not do enough research and ordered seats without a hole for the anti sub strap of a five pt so I was looking at the schroth 4pt w/asm, but I don't want to be hasseled at tech so maybe a 6pt is the answer if I can mount it to the lapbelt points.

Pete

[parsonsj]

Not all 6 points. Here's a couple examples (from the HMS Motorsport website):

PROFI 6-POINT AND HYBRID (tm) MODELS
• Anti-submarining strap routing shall be vertical down from the groin, preferably approximately 20° back.
(these attach through the seat)

PROFI F-MODELS
The anti-submarining strap routing over the upper thighs and attachment to the shoulder belt latches with the buckle in between, does not provide a direct load path from the shoulder belts down to the anti-submarining strap anchor points. The indirect routing requires a type of preloading of the anti-submarining straps during a frontal impact. This is achieved by sitting on the anti-submarining straps, routing them rearwards and attaching them in the region near or on the lap belt anchorages.
This anti-sub strap design requires sitting on the straps or having a thin seat panel allowing the straps running rearwards right underneath the driver’s buttock.
(these attach to the lap belt anchors)

[mikedc]

All this talk about seatbelts . . .

I don't think enough attention gets paid to the seat itself. A stock bucket seat from the 1960s has very little framework underneath.

I know for a fact that late-60s Mopar bucket seats can bend backwards with a normal size adult occupant in a hard rear-ender. And the typical GM & Ford seat frame of that era does not look any stronger in this respect.

.

[NOT A TA]

All this talk about seatbelts . . .

I don't think enough attention gets paid to the seat itself. A stock bucket seat from the 1960s has very little framework underneath.

I know for a fact that late-60s Mopar bucket seats can bend backwards with a normal size adult occupant in a hard rear-ender. And the typical GM & Ford seat frame of that era does not look any stronger in this respect.

.

Thats a good point but this thread was started about harnesses.

There are combinations of restraints/seats/roll protection that should only be used together as well as combinations that should be avoided. I've seen quite a few cars with hinged seats without a back brace and also have a roll bar with harness bar. I've also seen solid back seats in cars without a roll bar. Neither combination is correct. I'll be the first to admit I've run wrong combos in the past. I have a car now I had to remove the rollbar from, that has solid seats and had 5 point harnesses. I've been trying to figure out what to do about it since a new rollbar isn't in the budget right now.

Maybe a thread about proper seats for various applications should be started? Many hinged seats are designed to break if there's a rear impact. When a solid back should and shouldn't be used? Discuss seats refered to as "racing seats" that aren't really, and shouldn't be used as such, and so on. There's quite a few things people should know to get a combination that satisfies the needs and desires of the owner and is safe enough to pass tech inspections.

[JohnUlaszek]

Many hinged seats are designed to break if there's a rear impact..

I have never heard that before. Do you have any examples of this?